Multi coil array for wireless energy transfer with flexible device orientation

ABSTRACT

Various embodiments of inductor coils, antennas, and transmission bases configured for wireless electrical energy transmission are provided. These embodiments are configured to wirelessly transmit or receive electrical energy or data via near field magnetic coupling. The embodiments of inductor coils comprise a figure eight configuration that improve efficiency of wireless transmission efficiency. The embodiments of the transmission base are configured with at least one transmitting antenna and a transmitting electrical circuit positioned within the transmission base. The transmission base is configured so that at least one electronic device can be wirelessly electrically charged or powered by positioning the at least one device in contact with or adjacent to the transmission base.

RELATED APPLICATION

This application claims priority to U.S. Provisional Application No.62/511,688, filed on May 26, 2017, the disclosure of which is entirelyincorporated herein by reference.

TECHNICAL FIELD

The present disclosure generally relates to the wireless transmission ofelectrical energy and data. More specifically, this application relatesto various embodiments which enable the transmission of wirelesselectrical energy by near-field magnetic coupling.

BACKGROUND

Near field magnetic coupling (NFMC) is a commonly employed technique towirelessly transfer electrical energy. The electrical energy may be usedto directly power a device, charge a battery or both.

In NFMC an oscillating magnetic field generated by a transmittingantenna passes through a receiving antenna that is spaced from thetransmitting antenna, thereby creating an alternating electrical currentthat is received by the receiving antenna.

However, the oscillating magnetic field radiates in multiple directionsfrom the transmitting antenna. Thus, transmission of electrical energybetween opposed transmitting and receiving antennas may be inefficientas some of the transmitted magnetic fields may radiate in a directionaway from the receiving antenna.

In contrast to the prior art, the subject technology provides a wirelesselectrical power transmitting and receiving antenna and system thereofthat increases transmission of electrical energy therebetween,particularly in the presence of a metallic environment. Furthermore, incontrast to the prior art, the wireless electrical power transmittingsystem enables multiple electronic devices to be electrically charged orpowered by positioning one or more devices in non-limiting orientationswith respect to the transmitting antenna. Therefore, multiple devicesmay be electrically charged or powered simultaneously, regardless oftheir physical orientation with the transmitting antenna.

SUMMARY

The present disclosure relates to the transfer of wireless electricalenergy and/or data between a transmitting antenna and a receivingantenna. In one or more embodiments, at least one of a transmittingantenna and a receiving antenna comprising an inductor coil having afigure eight configuration is disclosed. In one or more embodiments, a“figure eight” coil configuration comprises at least one filar, formingthe coil, crosses over itself thereby forming a “figure-eight” coilconfiguration. Such an inductor coil configuration improves theefficiency of wireless electrical energy transmission by focusing theradiating magnetic field in a uniform direction, towards the receivingantenna. In one or more embodiments the figure eight coil configurationminimizes coupling of magnetic fields with the surrounding environmentthereby improving the magnitude and efficiency of wireless electricalenergy transmission.

In one or more embodiments, a wireless electrical power systemcomprising at least one transmitting and receiving antenna is disclosed.In one or more embodiments the at least one transmitting and receivingantenna of the electrical system comprises at least one inductor coilwith a figure eight configuration. In one or more embodiments, at leastone of the transmitting and receiving antennas of the wirelesselectrical power system may be configured within an electronic device.Such electronic devices may include, but are not limited to, consumerelectronics, medical devices, and devices used in industrial andmilitary applications.

In one or more embodiments at least one of the wireless electrical powertransmitting and receiving antennas is configured with one or moremagnetic field shielding embodiments that increase the quantity of themagnetic field within a given volume of space, i.e., density of themagnetic field that emanates from the antenna. In one or moreembodiments the wireless electrical power transmitting antenna isconfigured with one or more magnetic field shielding embodiments thatcontrol the direction in which the magnetic field emanates from theantenna. Furthermore, the transmitting and/or the receiving antenna isconfigured with one or more embodiments that increase the efficiency,reduces form factor and minimizes cost in which electrical energy and/ordata is wirelessly transmitted. As a result, the subject technologyprovides a wireless electrical energy transmission transmitting and/orreceiving antenna and system thereof that enables increased efficiencyof wireless electrical energy transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment of an inductor coil with a figure eightconfiguration of the present application.

FIG. 1A is a magnified view of the figure eight configurationillustrated in FIG. 1.

FIG. 2 shows an embodiment of an inductor coil that does not have afigure eight configuration.

FIG. 3 is a cross-sectional view showing an embodiment of thetransmission of a magnetic field between a transmitting antenna havingan inductor coil that is not of a figure eight configuration and areceiving antenna.

FIG. 4 is a cross-sectional view showing an embodiment of thetransmission of a magnetic field between a transmitting antenna havingan inductor coil with a figure eight configuration and a receivingantenna having an inductor coil with a figure eight configuration.

FIG. 5 illustrates an embodiment of an inductor coil with a figure eightconfiguration of the present application.

FIG. 5A is a magnified view of the figure eight configurationillustrated in FIG. 5.

FIG. 6 illustrates an embodiment of an inductor coil of a multiplefigure eight configuration of the present application.

FIG. 7 illustrates an embodiment of an inductor coil with a figure eightconfiguration of the present application.

FIG. 7A shows an embodiment of an equivalent circuit of the inductorcoil illustrated in FIG. 7.

FIG. 8 illustrates an embodiment of an inductor coil with a figure eightconfiguration of the present application.

FIG. 8A shows an embodiment of an equivalent circuit of the inductorcoil illustrated in FIG. 8.

FIG. 9 illustrates an embodiment of an inductor coil with a figure eightconfiguration of the present application.

FIG. 9A shows an embodiment of an equivalent circuit of the inductorcoil illustrated in FIG. 9.

FIG. 10 illustrates an embodiment of an inductor coil with a figureeight configuration of the present application supported on a substrate.

FIGS. 10A-10E are cross-sectional views of embodiments of inductor coilscomprising a figure eight configuration with various magnetic fieldshielding configurations.

FIGS. 11 and 12 show embodiments of spiral inductor coils that do nothave a figure eight configuration.

FIG. 13 is a cross-sectional view showing an embodiment of atransmitting antenna spaced from a receiving antenna used for electricalperformance testing.

FIG. 14 illustrates an embodiment of an inductor coil with a figureeight configuration of the present application.

FIG. 15 shows an embodiment of a parallel plate capacitor that may beelectrically incorporated with an inductor coil of the presentapplication.

FIGS. 16A-16C illustrate embodiments of an interdigitated capacitor thatmay be electrically incorporated with an inductor coil of the presentapplication.

FIG. 17 is a cross-sectional view showing an embodiment of atransmitting or receiving antenna of the present application.

FIG. 18 illustrates an embodiment of a transmitting antenna positionedopposed from a receiving antenna, both the transmitting and receivingantennas comprise magnetic field shielding material.

FIGS. 19, 20, and 21 show embodiments of an antenna array of the presentapplication.

FIG. 22 illustrates an embodiment of an electrical energy transmittingcradle comprising the inductor coil of the present application.

FIGS. 23A-23D illustrate embodiments of an electronic device positionedon the electrical energy transmitting cradle of the present application.

FIG. 24 illustrates an embodiment of an electrical energy transmittingbase comprising the inductor coil of the present application.

FIG. 24A illustrates an embodiment of an electronic device positioned onthe electrical energy transmitting base of the present application shownin FIG. 24.

FIGS. 25 and 26 show partially broken views of the electrical energytransmitting base of the present application shown in FIG. 24.

FIG. 27 illustrates an embodiment of an electrical energy transmittingbase comprising the inductor coil of the present application.

FIGS. 28A-28G illustrates an embodiment of a process of assembling atransmitting or receiving antenna of the present application.

FIGS. 29A-29C illustrates an embodiment of a process of assembling atransmitting or receiving antenna of the present application.

FIG. 30 is an exploded view of an embodiment of a transmitting orreceiving antenna of the present application.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth byway of examples in order to provide a thorough understanding of therelevant teachings. However, it should be apparent to those skilled inthe art that the present teachings may be practiced without suchdetails. In other instances, well known methods, procedures, components,and/or circuitry have been described at a relatively high-level, withoutdetail, in order to avoid unnecessarily obscuring aspects of the presentteachings.

The various embodiments illustrated in the present disclosure providefor the wireless transfer of electrical energy and/or data. Morespecifically, the various embodiments of the present disclosure providefor the wireless transmission of electrical energy and/or data via nearfield magnetic coupling between a transmitting antenna and a receivingantenna.

Now turning to the figures, FIG. 1 illustrates an example of aconfiguration of an antenna 10 of the present application. The antenna10 may be configured to either receive or transmit electrical energyand/or data via NFMC. In at least one or more embodiments, the antenna10 comprises at least one inductor coil 12 having at least one turnformed by at least one filar or wire 14. In at least one or moreembodiments, the inductor coil 12 is arranged in a configuration thatresembles a “figure-eight”. In one or more embodiments, the at least onefilar 14 forming the inductor coil 12 crosses over itself forming a“figure-eight” coil configuration. As illustrated in FIG. 1, theinductor coil 12 comprises at least one filar 14 that continuouslyextends from a first coil end 16 to a second coil end 18. In one or moreembodiments, the point at which the filar 14 crosses over itself betweenthe first and second ends 16, 18 is referred to as a crossoverintersection 20. In one or more embodiments, the filar 14 may have aconstant or a variable filar width.

As will be discussed in more detail, when configured within atransmitting antenna 22 (FIG. 4), the figure-eight coil configuration ofthe present application helps to focus magnetic fields 24 (FIG. 4) toemanate toward a receiving antenna 26 from the inductor coil 12 of thetransmitting antenna 22, thereby minimizing interference with a metallicobject or objects that may be positioned about the periphery of thetransmitting antenna 22. Furthermore, as a result of the figure-eightcoil configuration, coupling decreases between the transmitting antennaand external metallic objects, and in some cases increases between thetransmitting antenna 22 and a receiving antenna 26 (FIG. 4) whichresults in increased efficiency of the wireless transmission ofelectrical energy and/or data therebetween.

As illustrated in FIGS. 1, 1A, 5, 5A, and 6, in one or more embodiments,the crossover intersection 20 comprises a first filar portion 28 and asecond filar portion 30. As illustrated in FIGS. 1, 1A, 5, 5A, and 6,the first filar portion 28 crosses over the second filar portion 30 atthe crossover intersection 20. Likewise, the second filar portion 30 maycrossover the first crossover filar portion 28. Thus, as a result of thefigure eight construction, the inductor coil 12 comprises a firstinductor coil loop 32 comprising the first filar portion 28 and a secondinductor coil loop 34 comprising the second filar portion 30. FIG. 1Aillustrates a magnified view of an embodiment of the crossoverintersection 20 illustrated in FIG. 1.

In one or more embodiments, the inductor coil 12 comprising the figureeight construction may have an overlap area 36. As defined herein theoverlap area 36 is the area encompassed by the first filar portion 28and the second filar portion 30 (shown in FIG. 1A) that resides withineither of the first or second inductor coil loops 32, 34. FIG. 1illustrates an embodiment of the overlap area 36 encompassed by thefirst and second filar portions 28, 30 that resides within the firstinductor coil loop 32. In one or more embodiments, magnetic fields 24within the overlap area 36 cancel each other. In one or moreembodiments, the overlap area 36 may be configured to adjust theinductance exhibited by the inductor coil 12. In general, increasing thesize of the overlap area 36 decreases inductance and coupling exhibitedby the inductor coil 12 whereas decreasing the size of the overlap area36 increases the inductance and coupling exhibited by the inductor coil12.

In contrast to the figure eight coil configuration of the presentapplication, FIG. 2 illustrates an example of an inductor coil 38 thatdoes not comprise the figure eight configuration of the presentapplication. As shown the inductor coil 38 of FIG. 2 is of a spiralconfiguration in which the first coil end 16 resides at the end of theouter most coil turn and the second coil end 18 resides at the end ofthe inner most coil turn.

FIG. 3 illustrates a cross-sectional view of an embodiment of wirelesstransmission of electrical energy between a transmitting antenna 22 anda receiving antenna 26 in which both the transmitting and receivingantennas 22, 26 comprise a transmitting and receiving coil,respectively, lacking the figure-eight configuration. More specifically,in the embodiment shown in FIG. 3, the transmitting antenna 22 comprisesan inductor coil 38 that lacks the figure-eight coil configuration. Inone or more embodiments, as illustrated in FIG. 3, emanating magneticfields 24 follow a circular path around the current carrying filar 14 ofthe inductor coil 38. Further referencing the cross-sectional view ofFIG. 3, electrical current within the inductor coil 38 at the opposingleft and right coil ends shown in the cross-sectional view flows inopposite directions to each other, i.e., electrical current at the leftend flows in a left direction and the electrical current at the rightend, flows in a right direction. Furthermore, as the current electricalcurrent changes direction, i.e. from flowing in a left direction backtowards the right and vice versa within the inductor coil 38, thiscauses at least a portion of the emanating magnetic field 24 to follow apath away from the inductor coil 12 of the transmitting antenna 22 andcurve around an edge 40 of the transmitting antenna 22. As a result,efficiency of the wireless transmission of the electrical energy betweenthe transmitting antenna 22, having the inductor coil 38 not configuredwith a figure eight configuration, and the receiving antenna 26decreases as some of the emanating magnetic fields 24 do not contributeto the flux of the receiving antenna 22. Furthermore, a metallic object(not shown) positioned adjacent to the transmitting antenna 22 mayadversely interact with emanating magnetic fields 24 not emanatingdirectly towards the receiving antenna 26 such as the magnetic fields 24as illustrated travelling in a curved direction around the edge 40 ofthe transmitting antenna 22 in FIG. 3. As a result of this interactionbetween a portion of the emanating magnetic fields 24 and a metallicobject (not shown), the magnitude of transmitted electrical powerbetween the transmitting and receiving antennas 22, 26 is reduced.

In contrast to the inductor coil 38 illustrated in FIG. 2, the inductorcoil 12 of the present application comprises a figure eight constructionthat focuses the direction of the emanating magnetic fields 24 in auniform direction. Thus, spurious magnetic field emanating directionssuch as magnetic fields emanating in a curved or circular directionaround an edge 40 of the transmitting antenna 22, as illustrated in FIG.3, is minimized.

In one or more embodiments, magnetic fields 24 emanating from theinductor coil 12 of the subject technology having a figure eightconfiguration exhibit the pattern shown in FIG. 4. As illustrated in theembodiment shown in FIG. 4, magnetic fields 24 emanating from atransmitting antenna 22 comprising an inductor coil 12 having a figureeight configuration emanate in a direct, straight direction betweenopposing transmitting and receiving antennas 22, 26. As shown, in theembodiment of FIG. 4 a significantly reduced quantity of emanatingmagnetic fields 24, unlike the quantity of emanating magnetic fields 24shown in FIG. 3, curve around the respective edges 40 of thetransmitting antenna 22. This, therefore, increases efficiency and themagnitude of wireless electrical energy and/or data as an increasedamount of magnetic field 24 is directed from the transmitting antenna 22towards the receiving antenna 26. In addition, potential interferencewith a metallic object or objects (not shown) positioned adjacent to thetransmitting antenna 22 is minimized. As a result, coupling between thetransmitting antenna 22 and the receiving antenna 26 increases relativeto each other.

In one or more embodiments, the figure eight coil configuration of thepresent application creates an additional current carrying path at thecrossover intersection 20 that bisects the electrical current flowingthrough either of the first or second filar portions 28, 30. As aresult, there are three electrical currents at the crossoverintersection 20 instead of two electrical currents if not constructedwith the figure eight configuration. In one or more embodiments, thefilar 14 comprising the figure eight configuration crosses theintersection 20 twice in the same direction as compared to theelectrical current flowing within the inductor coil 12 at the respectivefirst and second inductor coil ends 16, 18 which flows in the samedirection with respect to each other. Therefore, the electrical currentat the crossover intersection 20 has a magnitude that is twice as greatas the electrical current at the respective first and second inductorcoil ends 16, 18. In one or more embodiments, the electrical currenthaving a greater magnitude flowing through the crossover intersection 20of the figure eight configuration thus forces the magnetic fields 24 toform opposing loop formations that are offset from the center of thecrossover intersection 20. These opposing magnetic field loop formationsthat are offset from the center of the crossover intersection 20 thuscreates a compact emanating magnetic field 24 that inhibits the magneticfield 24 from emanating in a spurious direction such as following acurved path around the edge 40 of the transmitting antenna 22.Furthermore, interference of the emanating magnetic field 24 with ametallic object or objects (not shown) that may be positioned adjacentto the transmitting antenna 22 is thus minimized or eliminated. As aresult, coupling and efficiency between transmitting and receivingantennas 22, 26 is increased. Furthermore, efficiency of wirelesselectrical energy transfer is increased.

In one or more embodiments, the first and second inductor loops 32, 34may be electrically connected in series, parallel, or a combinationthereof. In general, connecting the inductor loops in electrical seriesincreases inductance and series resistance. Connecting the inductorloops electrically in parallel generally decreases series resistance andinductance. In addition, in one or more embodiments, the first andsecond inductor coil loops 32, 34 may be positioned in opposition toeach other. In one or more embodiments, the first and second inductorcoil loops 32, 34 may be positioned diametrically opposed from eachother. In one or more embodiments, a crossover angle θ is createdbetween the first and second filar portions 28, 30. As defined herein,the crossover angle θ is the angle that extends between the first orsecond filar portion 28, 30 that extends over the other of the first orsecond filar portion 28, 30 at the crossover intersection 20. In one ormore embodiments, the crossover angle θ may be about 90°. In one or moreembodiments, the crossover angle θ may be greater than 0° and less than90°. In one or more embodiments, the crossover angle θ may be greaterthan 90° and less than 180°.

In this application, the subject technology concepts particularlypertain to NFMC. NFMC enables the transfer of electrical energy and/ordata wirelessly through magnetic induction between a transmittingantenna 22 and a corresponding receiving antenna 26 (FIG. 13). The NFMCstandard, based on near-field communication interface and protocolmodes, is defined by ISO/IEC standard 18092. Furthermore, as definedherein “inductive charging” is a wireless charging technique thatutilizes an alternating electromagnetic field to transfer electricalenergy between two antennas. “Resonant inductive coupling” is definedherein as the near field wireless transmission of electrical energybetween two magnetically coupled coils that are tuned to resonate at asimilar frequency. As defined herein, “mutual inductance” is theproduction of an electromotive force in a circuit by a change in currentin a second circuit magnetically coupled to the first circuit. Asdefined herein a “shielding material” is a material that captures amagnetic field. Examples of shielding material include, but are notlimited to ferrite materials such as zinc comprising ferrite materialssuch as manganese-zinc, nickel-zinc, copper-zinc, magnesium-zinc, andcombinations thereof. A shielding material thus may be used to direct amagnetic field to or away from an object, such as a parasitic metal,depending on the position of the shielding material within or nearby anelectrical circuit. Furthermore, a shielding material can be used tomodify the shape and directionality of a magnetic field. As definedherein a parasitic material, such as a parasitic metal, is a materialthat induces eddy current losses in the inductor antenna. This istypically characterized by a decrease in inductance and an increase inresistance of the antenna, i.e., a decrease in the quality factor. An“antenna” is defined herein as a structure that wirelessly receives ortransmits electrical energy or data. An antenna comprises a resonatorthat may comprise an inductor coil or a structure of alternatingelectrical conductors and electrical insulators. Inductor coils arepreferably composed of an electrically conductive material such as awire, which may include, but is not limited to, a conductive trace, afilar, a filament, a wire, or combinations thereof.

It is noted that throughout this specification the terms, “wire”,“trace”, “filament” and “filar” may be used interchangeably to describea conductor. As defined herein, the word “wire” is a length ofelectrically conductive material that may either be of a two-dimensionalconductive line or track that may extend along a surface oralternatively, a wire may be of a three-dimensional conductive line ortrack that is contactable to a surface. A wire may comprise a trace, afilar, a filament or combinations thereof. These elements may be asingle element or a multitude of elements such as a multifilar elementor a multifilament element. Further, the multitude of wires, traces,filars, and filaments may be woven, twisted or coiled together such asin a cable form. The wire as defined herein may comprise a bare metallicsurface or alternatively, may comprise a layer of electricallyinsulating material, such as a dielectric material that contacts andsurrounds the metallic surface of the wire. The wire (conductor) anddielectric (insulator) may be repeated to form a multilayer assembly. Amultilayer assembly may use strategically located vias as a means ofconnecting layers and/or as a means of creating a number of coil turnsin order to form customized multilayer multiturn assemblies. A “trace”is an electrically conductive line or track that may extend along asurface of a substrate. The trace may be of a two-dimensional line thatmay extend along a surface or alternatively, the trace may be of athree-dimensional conductive line that is contactable to a surface. A“filar” is an electrically conductive line or track that extends along asurface of a substrate. A filar may be of a two-dimensional line thatmay extend along a surface or alternatively, the filar may be athree-dimensional conductive line that is contactable to a surface. A“filament” is an electrically conductive thread or threadlike structurethat is contactable to a surface. “Operating frequency” is defined asthe frequency at which the receiving and transmitting antennas operate.“Self-resonating frequency” is the frequency at which the resonator ofthe transmitting or receiving antenna resonates.

In one or more embodiments, the inductor coils 12 of either thetransmitting antenna 22 or the receiving antenna 26 are strategicallypositioned to facilitate reception and/or transmission of wirelesslytransferred electrical power or data through near field magneticinduction. Antenna operating frequencies may comprise all operatingfrequency ranges, examples of which may include, but are not limited to,about 100 kHz to about 200 kHz (Qi interface standard), 100 kHz to about350 kHz (PMA interface standard), 6.78 MHz (Rezence interface standard),or alternatively at an operating frequency of a proprietary operatingmode. In addition, the transmitting antenna 22 and/or the receivingantenna 26 of the present disclosure may be designed to transmit orreceive, respectively, over a wide range of operating frequencies on theorder of about 1 kHz to about 1 GHz or greater, in addition to the Qiand Rezence interfaces standards. In addition, the transmitting antenna22 and the receiving antenna 26 of the present disclosure may beconfigured to transmit and/or receive electrical power having amagnitude that ranges from about 100 mW to about 100 W. In one or moreembodiments the inductor coil 12 of the transmitting antenna 22 isconfigured to resonate at a transmitting antenna resonant frequency orwithin a transmitting antenna resonant frequency band. In one or moreembodiments the transmitting antenna resonant frequency is at least 1kHz. In one or more embodiments the transmitting antenna resonantfrequency band extends from about 1 kHz to about 100 MHz. In one or moreembodiments the inductor coil 12 of the receiving antenna 26 isconfigured to resonate at a receiving antenna resonant frequency orwithin a receiving antenna resonant frequency band. In one or moreembodiments the receiving antenna resonant frequency is at least 1 kHz.In one or more embodiments the receiving antenna resonant frequency bandextends from about 1 kHz to about 100 MHz.

FIG. 5 illustrates an embodiment of a “digital” figure eight coilconstruction. As shown, the inductor coil 12 comprises a crossoverintersection 20 forming the first and second coil loops 32, 34. FIG. 5Aillustrates a magnified view of an embodiment of the crossoverintersection 20 shown in FIG. 5. In one or more embodiments, theinductor coil 12 is constructed such that adjacent segments of the firstand second filar portions 28, 30 are positioned about parallel to eachother. A digital figure eight gap 42 separates the adjacent segments ofthe first and second inductor coil loops 32, 34. As shown, a firstsegment 44 of the first inductor coil loop 32 is positioned parallel toa second segment 46 of the second inductor coil loop 34. Furthermore,the crossover can be used to modify the shape and directionality of amagnetic field for wireless power transfer.

In one or more embodiments, magnetic fields 24 typically combineaccording to the following mathematical relationship: I(R₁)+cos ϕ×I(R₂)where ϕ is the angle between the electrical current directions R₁ and R₂within each of the two inductor coil loops 32, 34. As illustrated inFIG. 5, since the inductor coil 12 comprises a digital figure eightconfiguration, the angle between the first and second inductor coilloops 32, 34 is 90°. Since the cosine of 90° is 0, the direction of themagnetic field 24 within the digital figure eight inductor coilconfiguration is in the same direction, I (R₁).

FIG. 6 illustrates an embodiment of an inductor coil 12 with a multiplefigure-eight configuration. As shown in the embodiment of FIG. 6, theinductor coil 12 comprises two cross over intersections 20 therebyforming three inductor coil loops, a first coil loop 32, a second coilloop 34, and a third coil loop 48. In an embodiment, constructing theinductor coil 12 with a multiple figure eight construction furtherfocuses the emitting magnetic field 24 and further strengthens couplingbetween the transmitting and receiving antennas 22, 26.

FIG. 7 illustrates an embodiment of an edge feed inductor coil 50comprising a figure eight configuration. As defined herein an edge feedinductor coil is an inductor coil configured to either transmit orreceive electrical energy via near field communication (NFC) in whichthe first and second ends 16, 18 of the inductor coil 50 are positionedat a side edge of the transmitting or receiving antenna 22, 26. FIG. 7Ashows an embodiment of an equivalent electrical circuit 52 of theinductor coil 50 shown in FIG. 7. As illustrated in FIG. 7A, theequivalent electrical circuit 52 comprises an inductor L₁ electricallyconnected between the first and second terminals 54, 56. In one or moreembodiments, as illustrated in FIG. 8, the inductor coil 12 may beconfigured in a center feed inductor coil 58 configuration. FIG. 8Ashows an embodiment of an equivalent electrical circuit 60 of theinductor coil 58 shown in FIG. 8. As illustrated in FIG. 8A, theequivalent electrical circuit 60 comprises an inductor L₂ electricallyconnected between the first and second terminals 54, 56. As definedherein a center feed coil is an inductor coil configured to eithertransmit or receive electrical energy via NFC in which the first andsecond ends 16, 18 of the inductor coil 58 are positioned at about thecenter of the inductor coil 58. In either of the edge feed or centerfeed inductor coil constructions 50, 58, electrical current flowsthrough the filars 14 of the inductor coils 50, 58 having a parallelorientation in the same direction. In one or more embodiments, the edgefeed 50 and/or the center feed 58 inductor coil configurations have twoinductor coil loops, a first inductor coil loop 32 and a second inductorcoil loop 34 respectively, that carry electrical current in oppositedirections to each other. Thus, the effective instantaneous magneticfield direction through the center of each first and second loops 32, 34of the edge feed inductor coil 50 and the center feed inductor coil 58is 180° off-phase.

FIG. 9 illustrates an embodiment of a parallel feed inductor coil 62. Inthis embodiment, a portion of the filar 14 that comprises the parallelfeed inductor coil 62 splits the inductor coil 62 into two inductor coilloops. Similar to the center and edge feed coil configurations 58, 50,electrical current travels in a parallel direction through the two loopsof the parallel feed inductor coil configuration 62 shown in FIG. 9. Inone or more embodiments, the parallel feed inductor coil configuration62 helps to reduce the inductance exhibited by the inductor coil 62.FIG. 9A shows an embodiment of an equivalent electrical circuit 64 ofthe inductor coil 62 shown in FIG. 9. As illustrated in FIG. 9A, theequivalent electrical circuit 64 comprises a first inductor L₃electrically connected in parallel to a second inductor L₄, the firstand second inductors L₃, L₄ electrically connected to the first andsecond terminals 54, 56.

In one or more embodiments, various materials may be incorporated withinthe structure of the inductor coils 12, 50, 58, 62 of the presentapplication to shield the inductor coils from magnetic fields and/orelectromagnetic interference and, thus, further enhance the electricalperformance of the respective transmitting or receiving antenna 22, 26.

In one or more embodiments, at least one magnetic field shieldingmaterial 66, such as a ferrite material, may be positioned about theinductor coil 12 or antenna 22, 26 structure to either block or absorbmagnetic fields 24 that may create undesirable proximity effects andthat result in increased electrical impedance within the transmitting orreceiving antenna 22, 26 and decrease coupling between the transmittingand receiving antennas 22, 26. These proximity effects generallyincrease electrical impedance within the antenna 22, 26 which results ina degradation of the quality factor. In addition, the magnetic fieldshielding material 66 may be positioned about the antenna structure toincrease inductance and/or act as a heat sink within the antennastructure to minimize over heating of the antenna. Furthermore, suchmaterials 66 may be utilized to modify the magnetic field profile of theantenna 22, 26. Modification of the magnetic field(s) 24 exhibited bythe antenna 22, 26 of the present disclosure may be desirable inapplications such as wireless charging. For example, the profile andstrength of the magnetic field exhibited by the antenna 22, 26 may bemodified to facilitate and/or improve the efficiency of wireless powertransfer between the antenna and an electric device 68 (FIG. 22) such asa cellular phone. Thus, by modifying the profile and/or strength of themagnetic field about an electronic device being charged, minimizesundesirable interferences which may hinder or prevent transfer of dataor an electrical charge therebetween.

FIGS. 10A, 10B, 10C, 10D, and 10E are cross-sectional views, referencedfrom the inductor coil 12 configuration shown in FIG. 10, illustratingvarious embodiments in which magnetic field shielding materials 66 maybe positioned about the inductor coil 12. As shown in thecross-sectional view of FIG. 10A, the inductor coil 12 may be positionedon a surface 70 of a substrate 72. In one or more embodiments, thesubstrate 72 may comprise the magnetic shielding material 66. FIG. 10Bis a cross-sectional view of an embodiment in which the inductor coil 12is positioned on a substrate 72 that comprises end tabs 74. Asillustrated, the end tabs 74 upwardly extend from the substrate surface70 at respective first and second ends 76, 78 of the substrate 72. Asillustrated, the end tabs 76, 78 have a height 80 that extends at leastto a top surface 82 of the inductor coil 12. As shown, the height 80 ofthe end tabs 74 extend beyond the top surface 82 of the inductor coil12. In one or more embodiments, the end tabs 74 have a thickness 84 thatextends from about 0.1 mm to about 100 mm FIG. 10C is a cross-sectionalview of an embodiment in which the inductor coil 12 may be positioned ona substrate 72 that comprises spaced apart first and second coilenclosures 86, 88. As illustrated, each enclosure 86, 88 extendsoutwardly from the substrate surface 70 at the respective first andsecond substrate ends 76, 78. In one or more embodiments, at least aportion of the filar 14 that comprises the inductor coil 12 ispositioned within at least one of the enclosures 86, 88. As shown inFIG. 10C the filar 14 forming the outermost segment of the first andsecond inductor coil loops 32, 34 are positioned within the respectiveenclosures 86, 88. FIG. 10D is a cross-sectional view of an embodimentin which a portion of the inductor coil 12 is positioned on a substrate72 comprising the magnetic shielding material 66. As shown, all but theouter most segment of the first and second inductor coil loops 32, 34are shown supported by the substrate 72. FIG. 10E is a cross-sectionalview of an embodiment in which at least a portion of the inductor coil12 is supported on a substrate 72 comprising the magnetic shieldingmaterial 66. In addition, the filar 14 forming the outermost segment ofthe first and second inductor coil loops 32, 34 are positioned withinspaced apart first and second inductor coil enclosures 86, 88. As shown,a gap 90 separates the substrate 72 supporting a portion of the inductorcoil 12 from the respective first and second enclosures 86, 88 thathouse outermost segments of the first and second inductor coil loops 32,34. In an embodiment, the substrate 72, end tabs 74 and enclosures 86,88 may comprise at least one magnetic field shielding material 66. It iscontemplated that more than one or a plurality of shielding materialsmay be used in a single structure or on a single layer of a multilayerstructure. Examples of the shielding material 66 may include, but arenot limited to, zinc comprising ferrite materials such asmanganese-zinc, nickel-zinc, nickel-iron, copper-zinc, magnesium-zinc,and combinations thereof. Further examples of shielding material 66 mayinclude, but are not limited to an amorphous metal, a crystalline metal,a soft ferrite material, a hard ferrite material and a polymericmaterial. As defined herein a soft ferrite material has a coercivityvalue from about 1 Ampere/m to about 1,000 Ampere/m. As defined herein ahard ferrite material has a coercivity value that is greater than 1,000Ampere/m. These and other ferrite material formulations may beincorporated within a polymeric material matrix so as to form a flexibleferrite substrate. Examples of such materials may include but are notlimited to, FFSR and FFSX series ferrite materials manufactured byKitagawa Industries America, Inc. of San Jose Calif. and Flux FieldDirectional RFIC material, manufactured by 3M® Corporation ofMinneapolis Minn.

The embodiments shown in FIGS. 10A-10E, illustrate non-limitingconfigurations that are designed to minimize magnetic fields 24 frommoving outward from within the area defined by the inductor coil 12.These illustrated embodiments are designed to help ensure that anincreased amount of magnetic fields 24 emanating from the transmittingantenna 22 reach the receiving antenna 26 and do not interfere withadjacently positioned metallic object(s) (not shown) as previouslydiscussed. In one or more embodiments, the magnetic field shieldingmaterial 66, such as a ferrite material, may have a permeability (mu′)that is greater than 1 at the operating frequency or frequencies of thetransmitting antenna 22 and/or the receiving antenna 22. In one or moreembodiments, the permeability of the ferrite material may be as great as20000 at the operating frequency or frequencies of the respectiveantenna 22, 26. In one or more embodiments, the magnetic shieldingmaterial 66 may also comprise an electrically conductive material.

In one or more embodiments, various electrical performance parameters ofthe wireless electrical energy transmitting and receiving antennas 22,26 of the present application were measured. One electrical parameter isquality factor (Q) defined below.

The quality factor of a coil defined as:

$Q = \frac{\omega*L}{R}$Where:

-   -   Q is the quality factor of the coil    -   L is the inductance of the coil    -   ω is the operating frequency of the coil in radians/s.        Alternatively, the operating frequency (Hz) may be ω divided by        2π    -   R is the equivalent series resistance at the operating frequency

Another performance parameter is resistance of receiving antennaefficiency (RCE) which is coil to coil efficiency. RCE is defined as:

${RCE} = \frac{k^{2}*Q_{Rx}*Q_{Tx}}{\left( {1 + \sqrt{\left( {1 + {k^{2}*Q_{rx}*Q_{tx}}} \right)}} \right)^{2}}$Where:

-   -   RCE is the coil to coil efficiency of the system    -   k is the coupling of the system    -   Q_(rx) is the quality factor of the receiver    -   Q_(tx) is the quality factor of the transmitter

Another performance parameter is mutual induction (M). “M” is the mutualinductance between two opposing inductor coils of a transmitting andreceiving antenna, respectively. Mutual induction (M) is defined as:

$M = \frac{V_{induced}}{\omega*I_{Tx}}$Where:

-   -   V_(induced) is induced voltage on the receiver coil    -   I_(tx) is the alternating current (AC) flowing through the        transmitter coil    -   ω is the operating frequency multiplied by 2π

Mutual inductance can be calculated by the following relationship:M=k*√{square root over (L _(Tx) L _(Rx))}Where:

-   -   M is the mutual inductance of the system    -   k is the coupling of the system    -   L_(Tx) is the inductance of the transmitter coil    -   L_(Rx) is the inductance of the receiver coil

Figure of Merit (FOM) can be calculated by the following relationship:

${FOM} = {M^{2}\frac{\omega^{2}}{R_{TX}R_{RX}}}$Where:

FOM is the figure of merit

ω is the operating frequency in radians

R_(TX) is the AC electrical resistance of the transmitting coil at theoperating frequency

R_(RX) is the AC electrical resistance of the receiving coil at theoperating frequency

M is the mutual inductance

Coil to Coil Efficiency (C2C) can be calculated by the followingrelationship:

${C\; 2\; C\mspace{14mu}{efficiency}} = \frac{FOM}{\left( {1 + \sqrt{1 + {FOM}}} \right)^{2}}$Where:

-   -   FOM is the figure of merit

Table I shown below, delineates the inductance (L), electricalresistance (R), and quality factor (Q) of both the transmitting andreceiving antennas 22, 26 that comprised an inductor coil configuredwithout the figure eight configuration. FIG. 11 illustrates anembodiment of a transmitting inductor coil 92 that was used in theperformance testing detailed in Table I. As shown in FIG. 11, thetransmitting inductor coil 92 comprised a spiral configuration having anouter diameter of 27 mm and 5 turns. FIG. 12 illustrates an embodimentof a receiving inductor coil 94 that was used in the performance testingdetailed in Table I. As illustrated, the receiving inductor coil 94,comprised a spiral configuration with an outer diameter of 29.4 mm and 4turns. It is noted that both the transmitting and receiving inductorcoils 92, 94 shown in FIGS. 11 and 12 respectively and used in theperformance testing detailed in Table I, did not comprise a figure eightconfiguration. Furthermore, the transmitting antenna 22 comprising thetransmitting inductor coil 92 was positioned about 3.5 mm from thereceiving antenna 26 that comprised the receiving inductor coil 94during the performance testing as illustrated in FIG. 13. Configuration1 comprised the transmitting antenna 22 with only the transmittinginductor coil 92. Configuration 2 included the transmitting inductorcoil 92 supported by a core 95 of magnetic field shielding material 66comprising for example, but not limited to, Mn—Zn, Ni—Zn, soft ferrites,hard ferrites, Mu-Metals, amorphous metal sheets, nano-crystalline metalsheets, polymer based magnetic shielding, and having a thickness ofabout 0.3 mm. Configuration 3 comprised the receiving antenna 26 withonly the receiving inductor coil 94. Configuration 4 comprised thereceiving inductor coil 94 supported by the core 95 of magnetic fieldshielding material comprising materials as discussed for Configuration2, and having a thickness of about 0.1 mm. Configuration 5 was of thereceiving inductor coil 94 supported by the core 95 of magnetic fieldshielding material comprising materials as discussed for Configuration2, and surrounded by an aluminum ring 96 having a thickness of about 0.2mm. FIG. 13 illustrates the performance test configuration with thetransmitting antenna 22 configured in configuration 2 and the receivingantenna 26 in configuration 5. The mutual inductance between thetransmitting antenna 22 of configuration 2 and the receiving antenna 26of configuration 4 was about 300.7 nH. The mutual inductance between thetransmitting antenna 22 of configuration 2 and the receiving antenna 26of configuration 5 was about 275 nH. Thus, the metal ring positionedaround the circumference of the receiving inductor coil 94 decreasedmutual inductance by about 25.7 nH or by about 8.5 percent.

TABLE I L R (nH) (Ohms) Q Transmitting Antenna Configuration 1 467 nH0.17 117 Configuration 2 666.3 nH   0.435 65.22 Receiving AntennaConfiguration 3 618 nH 0.2 131.6 Configuration 4 720.7 nH   0.32 154Configuration 5 575 nH 0.51 48

As detailed in the test performance results shown in Table I, inclusionof the magnetic field shielding material 66 increased the inductance ofboth the transmitting and receiving antennas 22, 26. In addition,inclusion of the magnetic field shielding material 66 increased thequality factor of the receiving antenna 26.

Table II shown below delineates the inductance (L), electricalresistance (R), and quality factor (Q) of both the transmitting andreceiving antennas 22, 26 that comprised an inductor coil 12 having thefigure eight configuration. FIG. 14 illustrates an embodiment of atransmitting inductor coil 98 and a receiving inductor coil 100 utilizedin the performance testing detailed in Table II. The transmittinginductor coil 98 comprised a spiral configuration having an outerdiameter of 27 mm, 3 turns and a figure eight configuration. Thereceiving inductor coil 100 also comprised a spiral configuration withan outer diameter of 27 mm, 3 turns, and a figure eight configuration.The transmitting antenna 22 was positioned about 3.5 mm from thereceiving antenna 22. Configuration 1 comprised the transmitting antenna22 with only the transmitting inductor coil 98. Configuration 2 includedthe transmitting inductor coil 98 supported by a magnetic fieldshielding material 66 comprising zinc and having a thickness of about0.3 mm. Configuration 3 was of the receiving antenna 26 comprising onlythe receiving inductor coil 100. Configuration 4 comprised the receivinginductor coil 100 supported by the magnetic field shielding materialcomposed of nickel, zinc, copper ferrite having a thickness of about 0.1mm. Configuration 5 was of the receiving inductor coil 100 supported bythe ferrite material that was surrounded by an aluminum ring 96 having athickness of about 0.2 mm. FIG. 13 illustrates the test configuration ofthe transiting antenna 22 in confirmation 2 and the receiving antenna 26in configuration 5. The mutual inductance between the transmittingantenna 22 of configuration 2 and the receiving antenna 26 ofconfiguration 4 was about 412 nH. The mutual inductance between thetransmitting antenna 22 of configuration 2 and the receiving antenna 26of configuration 5 was about 411 nH. Thus, the metal ring 96 positionedaround the circumference of the receiving inductor coil 100 decreasedthe mutual inductance by about 1 nH or decreased by about 0.2 percent.

TABLE II L R (ohms) Q Transmitting Antenna Configuration 1 805 nH 0.5661.23 Configuration 2 1.135 μH   0.66 73.26 Receiving AntennaConfiguration 3 805 nH 0.56 61.23 Configuration 4  1.1 μH 0.72 65Configuration 5  1 μH 0.77 55.32

As detailed in the test performance results shown in Table II, inclusionof the magnetic field shielding material 66 increased the inductance ofboth the transmitting and receiving antennas 22, 26. In addition,inclusion of the magnetic field shielding material 66 increased thequality factor of the transmitting and receiving antennas 22, 26.

In one or more embodiments a capacitor such as a surface mount capacitormay be electrically connected to the inductor coil 12. In one or moreembodiments, a capacitor can be electrically connected to the inductorcoil 12 of the transmitting antenna 22 and/or the receiving antenna 26to adjust the inductance of the inductor coil 12. The capacitor maycomprise a parallel plate capacitor 102 and/or an interdigitatedcapacitor 104. In one or more embodiments, the capacitor, such as aparallel plate capacitor 102 or an interdigitated capacitor 104 may befabricated on or incorporated within a substrate that supports theinductor coil 12. For example, a parallel plate capacitor 102 or aninterdigitated capacitor 104 may be fabricated on or within a printedcircuit board (PCB) or flexible circuit board (FCB) to impart a desiredcapacitance to the transmitting or receiving antenna 22, 26. FIG. 15illustrates examples of a parallel plate capacitor 102 and aninterdigitated capacitor 104. The benefit of utilizing a parallel platecapacitor 102 or an interdigitated capacitor 104 configuration is thatthey provide a robust thinner design that is generally of a lower cost.

In one or more embodiments, the parallel plate capacitor 102, as shownin FIG. 15, comprises a dielectric material 106 positioned between twoopposing electrically conducting plates 108 positioned in parallel toeach other.

Non-limiting examples of an interdigitated capacitor 104 are shown inFIGS. 15 and 16A-16C. In one or more embodiments, as illustrated inFIGS. 15 and 16A-16C interdigitated capacitors 104 typically have afinger-like shape. In one or more embodiments, the interdigitatedcapacitor 104 comprises a plurality of micro-strip lines 110 thatproduce high pass characteristics. The value of the capacitance producedby the interdigitated capacitor 104 generally depends on variousconstruction parameters. These include, a length 112 of the micro-stripline 110, a width 114 of the micro-strip line 110, a horizontal gap 116between two adjacent micro-strip lines 110, and a vertical gap 118between two adjacent micro-strip lines 110 (FIG. 16A). In one or moreembodiments, the length 112 and width 114 of the micro-strip line 110can be from about 10 mm to about 600 mm, the horizontal gap 116 can bebetween about 0.1 mm to about 100 mm, and the vertical gap 118 can bebetween about 0.0001 mm to about 2 mm.

In one or more embodiments, the inter-digitated capacitor 104 can beintegrated within a substrate 120 such as a PCB. In one or moreembodiments, the inductor coil 12 may be positioned on the surface ofthe interdigitated capacitor 104. Alternatively, the inductor coil 12may be positioned surrounding the interdigitated capacitor 104. In oneor more embodiments, the interdigitated capacitor 104 may be positionedwithin an opening or cavity (not shown) within a substrate 72 supportingthe inductor coil 12. In one or more embodiments, the interdigitatedcapacitor 104 provides a cost-effective means to add capacitance to theinductor coil 12. In addition, the interdigitated capacitor 104 ismechanically durable and may be used to connect a tuned inductor coil 12directly to a circuit board. In one or more embodiments, interdigitatedcapacitors 104 can also be useful in applications where relatively thinform factors are preferred. For example, an interdigitated capacitor 104may be used to tune the inductor coil 12 in lieu of a surface mountcapacitor because of the mechanical robustness, relatively thin design,and reduced cost of the interdigitated capacitor 104.

FIG. 17 illustrates a cross-sectional view of one or more embodiments ofan inductor coil 12 supported on the surface 70 of a substrate 72. Asshown in the embodiment, three sections of filar 14 are illustrated onthe surface 70 of the substrate 72. In one or more embodiments, an airgap 122 extends between adjacently positioned sections of filar 14. Asshown each of the sections of filar 14 comprises a filar section width124 that extends about parallel to the surface 70 of the substrate 72between filar section sidewalls 126. In addition, each of the sectionsof filar 14 comprise a thickness 128 that extends from the surface 70 ofthe substrate 72 to a top surface 130 of the filar. In addition, anelectrically conductive via 132 is shown electrically connected to thefilar 14 extending through the thickness of the substrate 72.

In one or more embodiments, the width of the air gap 122 that extendsbetween sidewalls 126 of adjacently positioned filars 14 is minimized.In one or more embodiments, decreasing the width of the air gap 122 mayincrease the amount of electrically conductive material that comprisesthe filar 14 within a defined area. Thus, the amount of electricalcurrent and magnitude of electrical power able to be carried by theinductor coil 12 within a specific area is increased. For example,decreasing the air gap 122 between adjacent filars 14 would enable anincreased number of coil turns within a specified area. In one or moreembodiments, the width of the air gap 122 may range from about 10 μm toabout 50 μm. In one or more embodiments, the width of the air gap 122may range from about 15 μm to about 40 μm.

In one or more embodiments, the thickness 128 of the filar that extendsfrom the surface 70 of the substrate 72 is maximized. In one or moreembodiments, increasing the thickness 128 of the filar 14 increases theamount of electrically conductive material that comprises the filarwithin a defined area. Thus, the amount of electrical current andmagnitude of electrical power able to be carried by the inductor coil 12is increased within a specific area. In one or more embodiments, thethickness 128 of the filar 14 may vary or be constant along the inductorcoil 12. In one or more embodiments, the thickness 128 of the filar 14may range from about 12 μm to about 150 μm. In one or more embodiments,the width 124 of the filar 14 may vary or be constant along the inductorcoil 12. In one or more embodiments, the width 124 of the filar 14 mayrange from about 10 μm to about 100,000 μm.

In one or more embodiments, the ratio of the width of the air gap 122 tothe filar thickness 128 is minimized. In one or more embodiments, theratio of the width of the air gap 122 to the filar thickness may rangefrom about 0.10 to about 0.50. In one or more embodiments, the ratio ofthe width of the air gap to the filar thickness may range from about0.30 to about 0.40.

In one or more embodiments, the sidewall 126 of the filar 14 is orientedabout perpendicular to the surface 70 of the substrate 72. In one ormore embodiments, the sidewall 126 of the filar 14 may be oriented at asidewall angle τ with respect to the surface 70 of the substrate 72. Asdefined herein, the sidewall angle τ is the angle between the exteriorsurface of the filar sidewall 126 and the surface 70 of the substrate 72on which the filar 14 is supported. In one or more embodiments, thesidewall angle τ may range from about 75° to about 90°.

TABLE III Antenna Inductance ESR Inductance ESR Config (μH) (ohms) Q(μH) (ohms) Q Parameter 1 Parameter 2 1 5.77 0.211 17.18 5.72 0.25414.14 2 5.91 0.508 7.30 5.34 0.624 5.37 3 5.08 0.642 4.97 3.69 0.8152.84

Table III above illustrates how the electrical performance ofinductance, equivalent series resistance (ESR), and quality factor (Q)change using an air gap of different widths. As shown in Table IIIabove, computer simulations of three different antenna coilconfigurations were modeled having two different air gap widths. Antennacoil configuration 1 comprised an inductor coil 12 of a rectangularconfiguration having a length and width of 40 mm and 12 turns. Antennacoil configuration 2 comprised an inductor coil 12 of a circularconfiguration having an outer diameter of 17 mm. Configuration 2 furthercomprised two coils, a first coil having 12 turns supported on a topsurface of a substrate comprising an electrically insulative materialand a second coil comprising 12 turns supported on an opposed bottomsurface of the substrate. Antenna coil configuration 3 comprised aninductor coil of a circular configuration having an outer diameter of 17mm. Configuration 3 further comprised two coils, a first coil having 14turns supported on a top surface of a substrate comprised of anelectrically insulative material and a second coil comprising 14 turnssupported on an opposed bottom surface of the substrate. Each of thethree antenna coil configurations was modeled having two different airgap widths. Antenna coil configurations 1-3 of Parameter 1 were modeledcomprising an air gap width of 0.020 μm whereas antenna coilconfigurations 1-3 of Parameter 2 were modeled having an air gap widthof 0.160 μm. The antenna coil configurations of each parameter comprisedthe same number of turns but different air gap widths 0.20 μm(Parameter 1) and 0.160 μm (Parameter 2) between adjacent filars 14. Asdetailed in Table III above, reducing the width of the air gap 122increased inductance, quality factor, and reduced equivalent seriesresistance.

FIG. 18 illustrates one or more embodiments of a transmitting antenna 22comprising magnetic field shielding materials 66 positioned opposed andspaced apart from a receiving antenna 26 comprising magnetic fieldshielding material 66. As illustrated, in the embodiment shown in FIG.18, the transmitting antenna 22 comprises a transmitting inductor coil98 having the figure eight configuration supported on a substrate 72comprising the magnetic field shielding material 66. The receivingantenna 26 positioned spaced from the transmitting antenna 22 comprisesa receiving inductor coil 100 with the figure eight configuration. Thereceiving inductor coil 100 is supported by a substrate 72 comprisingthe magnetic field shielding material 66. A ground plane 134 comprisingan electrically conductive material supports the magnetic fieldshielding material 66 and the receiving inductor coil 100. A metal ring136 having an inner circumference about equal to an outer diameter ofthe transmitting inductor coil 98 is positioned in a gap 138 positionedbetween the transmitting and receiving antennas 22, 26.

In one or more embodiments the inductor coil 12 and antenna 22, 26concepts of the present application, may be used to form a multi-antennaarray 140 as illustrated in FIGS. 19 and 20. In addition to an inductorcoil 12 having a figure eight configuration of the present application,the multi-antenna array 140 may also comprise inductor coils 12 having avariety of non-limiting configurations such as a spiral, a solenoid orcombination thereof. Further examples of wireless antenna structuresthat may be incorporated within the multi-antenna array may include butare not limited to antennas disclosed in U.S. Pat. Nos. 9,941,729;9,941,743; 9,960,628; and U.S. patent application Ser. Nos. 14/821,177;14/821,236; and 14/821,268 all to Peralta et al.; U.S. Pat. Nos.9,948,129, 9,985,480 to Singh et al.; U.S. Pat. No. 9,941,590 toLuzinski; and U.S. Pat. No. 9,960,629 to Rajagopalan et al., all ofwhich are assigned to the assignee of the present application andincorporated fully herein. Non-limiting examples of antennas having amultilayer multiturn (MLMT) construction that may be incorporated withthe present disclosure may be found in U.S. Pat. Nos. 8,610,530;8,653,927; 8,680,960; 8,692,641; 8,692,642; 8,698,590; 8,698,591;8,707,546; 8,710,948; 8,803,649; 8,823,481; 8,823,482; 8,855,786;8,898,885; 9,208,942; 9,232,893; and 9,300,046 all to Singh et al., andassigned to the assignee of the present application are incorporatedfully herein. It is also noted that other antennas such as, but notlimited to, an antenna configured to send and receive signals in the UHFradio wave frequency such as the IEEE standard 802.15.1 may beincorporated within the present disclosure.

In one or more embodiments, the multi-antenna array 140 of the presentapplication may comprise a multitude of transmitting and/or receivinginductor coils 98, 100 that are positioned embedded within a platform142 (FIG. 20). In one or more embodiments, the multi-antenna array 140within the platform 142 is configured so that electrical energy and/ordata may be wirelessly transmitted or received to or from at least oneelectronic device 68, such as a cellular phone. The electrical energyand/or data may be wirelessly transmitted to or received from arespective electronic device 68 by positioning the device 68 on or nearthe platform 142 in a variety of unlimited positions. For example, anelectronic device 68, i.e., a cellular phone or watch, configured with awireless NFMC receiving antenna 26 may be electrically charged ordirectly powered by positioning the device 68 in a multitude oforientations with respect to the multi-coil array 142 of the presentapplication. In one or more embodiments, the multi-antenna array isconfigured having an inductance ranging from about 50 nH to about 50 μH.Thus, the multi-antenna array 140 of the present application may beconfigured with a multitude of inductor coils 12 that are specificallytuned to a variety of operating frequencies. These frequencies includebut are not limited to between 50 kHz to about 500 kHz as well as fromabout 6.78 MHz to about 276.12 MHz. This, therefore, enables thewireless transmission of electrical energy and/or data to a multitude ofunlimited electronic devices 68.

FIGS. 19 and 20 illustrate non-limiting embodiments of the multi-antennaarray 140 of the present application. FIG. 19 illustrates an embodimentin which three inductor coils 12, 98, 100 are arranged in a specificpattern. As shown, a first inductor coil 144 and a second inductor coil146 are positioned parallel and co-planar to each other. A thirdinductor coil 148 is positioned above the first and second inductorcoils 144, 146. As illustrated in the embodiment shown in FIG. 19 thethird inductor coil 148 is positioned perpendicular to the first andsecond inductor coils 144, 146 oriented parallel to each other. Inaddition, the third inductor coil 148 is positioned extending betweenand at least partially overlapping the first and second inductor coils144, 146. An imaginary line A-A extends lengthwise, bisecting the thirdinductor coil 148. Furthermore, the embodiment of the multi-antennaarray shown in FIG. 19 is arranged such that the imaginary line A-Aextends widthwise and bisects the first and second inductor coils 144,146. In one or more embodiments, the multi-antenna array 140 of FIG. 19may be constructed such that an antenna arrangement distance 150 extendsbetween the bisect of the third inductor coil 148 and either of thebisect of the first or second inductor coils 144, 146 is about equal.

FIGS. 20 and 21 illustrate one or more embodiments of a multi-antennaarray 140. As shown, three inductor coils 12, 98, 100 are arranged in afan-like arrangement. In one or more embodiments as shown in FIGS. 20and 21, a third inductor coil 148 is positioned between first and secondinductor coils 144, 146. In the embodiment shown in FIGS. 20 and 21, thefirst and second inductor coils 144, 146 are positioned about co-planarto each other. The third inductor coil 148 is positioned in a planeabove the first and second inductor coils 144, 146. Alternatively, thethird inductor coil 148 may be positioned on a plane below the first andsecond inductor coils 144, 146. In one or more embodiments, the inductorcoils 144, 146, 148 of the multi-antenna array 140 shown in FIGS. 20 and21 are oriented in an angular relationship with respect to each other.As illustrated an imaginary line B-B extends lengthwise and bisects thefirst inductor coil 144 of the array 140. A second imaginary line C-Cextends lengthwise and bisects the second inductor coil 146 of the array140. A third imaginary line D-D extends lengthwise and bisects the thirdinductor coil 148 of the array 140. In one or more embodiments, a firstinductor coil array angle γ extends between the imaginary line A-A thatextends through the first inductor coil 144 and the imaginary line D-Dthat extends through the third inductor coil 148. A second inductor coilarray angle κ extends between the imaginary line C-C that extendsthrough the second inductor coil 146 and the imaginary line D-D thatextends through the third inductor coil 148. In one or more embodiments,at least one of the first and second inductor coil array angles γ, κ mayrange from about 1° to about 90°. In one or more embodiments, the firstand second inductor coil array angles γ, κ may be about equal to eachother. In one or more embodiments, the first and second inductor coilarray angles γ, κ may not be about equal to each other.

In one or more embodiments, the multi-antenna arrays 140 illustrated ineither or both FIG. 19, 20, or 21 may be embedded within a platform 142or substrate 72. In one or more embodiments, the multi-antenna array 140may be embedded within the platform 142 such that the top surface of atleast one of the inductor coils 144, 146, 148 of the array 140 ispositioned flush with the top surface of the platform 142. In one ormore embodiments, a potting compound may be used to embed themulti-antenna array 140 within the platform 142 or substrate 72. In oneor more embodiments, the potting compound may comprise but is notlimited to an adhesive, a thermosetting adhesive, a polymeric material,a thermoplastic polymer, a dielectric material, a metal, or a ceramicmaterial. In one or more embodiments, the potting compound may have athermal conductivity equal to or greater than 1.0 W/(M•K).

In one or more embodiments, the multi-antenna array 140 of the presentapplication may be configured in a wireless electrical energytransmitting cradle 152 shown in FIGS. 22 and 23A-23D.

In one or more embodiments, as illustrated in FIG. 21, at least oneplatform 142 comprising the multi-antenna array 140 is electricallyconfigured within the electrical energy transmitting cradle 152. In oneor more embodiments, electrical wiring 154 (FIG. 21) connected to eachof the inductor coils 144, 146, 148 is electrically connected to amicro-control unit (not shown) residing within the electrical energytransmitting cradle 152. In one or more embodiments, an electrical powersource (not shown) is electrically connectable to the micro-control unitand each of the inductor coils 144, 146, 148 of the multi-antenna array140. In one or more embodiments, the micro-control unit may beconfigured to detect the presence of an electronic device 68 positionednear at least one of the inductor coils of the multi-antenna array 140.In addition, in one or more embodiments, the micro-control unit isconfigured to electrically switch between any individual or acombination of inductor coils 144, 146, 148 to ensure proper wirelesstransmission or reception of electrical energy between the cradle 152and at least one electronic device 68. Examples of such devices includebut are limited to a cellular phone, a computer, a radio, or a wearableelectronic device.

As illustrated in FIGS. 22 and 23A-23D, the electrical transmittingcradle 152 comprises at least one platform 142 comprising themulti-antenna array 140. In addition, the electrical transmitting cradle152 may comprise a housing 156 and at least one sidewall 158. The atleast one sidewall 158 is designed to hold the electronic device 68within the cradle 152 during electrical energy transfer therebetween. Inone or more embodiments, the at least one sidewall 158 may comprise atleast one multi-antenna array 140 therewithin thereby enabling wirelesselectrical energy transmission between the cradle 152 and an electronicdevice 68 positioned therewithin in an unlimited number of orientationswith respect to an inductor coil of the array 140. In one or moreembodiments, the at least one sidewall 158, multi-antenna array platform142, and/or housing 156, may be configured with an angular orientationwith respect to each other. Thus, the electrical transmitting cradle 152is designed to be mechanically sturdy and help prevent an electronicdevice 68 such as a cellular phone from falling off the cradle 152.FIGS. 23A-23D illustrate various non-limiting orientations within whichan electronic device 68, i.e., a cellular phone may be positioned withinthe cradle 152 and still enable wireless transmission of electricalenergy and/or data therebetween.

FIGS. 24, 24A, 25, 26, and 27 illustrate one or more embodiments of awireless electrical energy transmitting base 160 that comprises themulti-antenna array 140 of the present application. As shown, thewireless transmitting base 160 comprises a base housing 162 and aplurality of wireless transmission surfaces 164 that are positionedabout the wireless transmitting base 160. In one or more embodiments, atleast one of the multi-antenna array 140 is positioned within the basehousing 162. FIG. 23A illustrates an example of an electronic device 68,i.e., a cellular phone, positioned in contact with the transmissionsurface 164 of the base 160. In one or more embodiments, the wirelessenergy transmission base 160 is configured so that at least oneelectronic device 68 is capable of being electrically charged and/ordirectly powered from electrical energy wirelessly transmitted from thebase 160. The at least one electronic device may be positioned incontact with at the least one of the transmission surface 164 oralternatively, the at least one electronic device 68 may be positionedadjacent to but not in direct contact with the at least one of thetransmission surface 164.

In one or more embodiments as illustrated in FIGS. 25 and 26, thewireless transmitting base 160 comprises a circuit board 166 positionedwithin the base housing 162. In one or more embodiments, the circuitboard 166 comprises at least one micro-control unit 168 that controlsthe operation of each of the inductor coils that comprise themulti-antenna array 140 positioned within the base housing 162. In oneor more embodiments, the micro-control unit 168 may be configured toswitch between each individual or a combination of inductor coils. Inone or more embodiments, the micro-control unit 168 may be configured todetect the presence of an electronic device 68 and direct wirelesselectrical power to the device 68. In one or more embodiments, the microcontrol unit 168 is configured to direct electrical power to bewirelessly transmitted by controlling various resistors, inductors,and/or capacitors (not shown) within the wireless electrical energytransmitting base 160 to activate or deactivate specific paths ofelectrical energy within the base 160.

In one or more embodiments either or both the transmitting inductor coil98 and the receiving inductor coil 100 of the present application may befabricated using a laser (not shown). In one or more embodiments, thelaser may be used to cut the electrically conductive material, therebyforming the filar or wire 14 of the respective inductor coil 12 andfurther join components together. In one or more embodiments, the lasermay be used to cut the electrically conductive material of the coilfilar 14 to exacting tolerances. In one or more embodiments, the lasermay also be used to join components of the inductor coil and/or antenna12, 22, 26.

FIGS. 28A-28G and 29A-29C illustrate embodiments of a process offabricating a transmitting or receiving antenna 22, 26 of the presentapplication. In one or more embodiments, a laser (not shown) may be usedto fabricate the antenna. FIG. 28A illustrates step one of the processin which at least o first opening 170 is formed through a substrate 172.In one or more embodiments the substrate 172 is composed of a polymermaterial. FIG. 28B illustrates an embodiment of step two of the processin which at least one, second opening 174 is formed through an adhesivesheet 176 and placed in contact with either the top or bottom surface ofthe substrate 172. In one or more embodiments, at least one adhesivesheet 176 is positioned on both the top and bottom surfaces of thesubstrate 172. In one or more embodiments, the adhesive sheet 176 ispositioned on the surface of the substrate 172 so that the secondopenings 174 of the adhesive sheet 176 align with the first openings 170of the substrate 172. FIG. 28C illustrates an embodiment of step threeof the process in which at least one electrically conductive material178 such as a metal substrate is positioned on at least the top andbottom surface of the adhesive sheet 176. As illustrated two coppersubstrates are adhered to the top and bottom surfaces of the adhesivesheet 176. FIG. 28D illustrates step four of the process in which theelectrically conductive material is cut into wire or filar 14 strandsthereby forming the inductor coil 12. In one or more embodiments, alaser can be used to cut the electrically conductive material into thewire or filar strands 14. FIG. 28E illustrates step five of the process.In one or more embodiments, at least two of the wires or filars 14 arejoined together. In one or more embodiments, at least two of the wiresor filars 14 are welded together, for example with a laser forming aweld joint 180 therebetween. In one or more embodiments, a protectivesubstrate 182 such as a polymer film is applied to at least the top andtop surfaces of the electrically conductive material 178 that forms thefilar 14 of the inductor coil 12. FIG. 28G illustrates step six of theprocess in which a metallic substrate 184 is poisoned in contact with atleast one of the top and bottom surfaces of the protective substrate182. In one or more embodiments, the metallic substrate 184 acts as abarrier to protect the inductor coil 12 from potential damage.

FIGS. 29A-29C illustrate one or more embodiments of a process offabricating a transmitting or receiving antenna 22, 26 of the presentapplication. FIG. 29A illustrates an embodiment of the first step in theprocess in which an adhesive sheet 176 comprising at least one firstopening 170 is applied to at least the top or bottom surface of asubstrate 172 such as a polymer substrate. In one or more embodiments,the substrate 172 has at least one, second opening 174. In one or moreembodiments, the first opening 170 of the adhesive sheet 176 aligns withthe at least one second opening 174 of the substrate 172. FIG. 29Billustrates an embodiment of step two of the process in which anelectrically conductive material 178 such as a metal substrate ispositioned in contact with at least one surface of the adhesive sheet176. FIG. 29C illustrates an embodiment of the third step in the processin which the electrically conductive material 178 is cut to form thewires or filars 14 that comprise the inductor coil 12.

FIG. 30 illustrates one or more embodiments of an inductor coil assembly186 of the present application. As illustrated, the assembly 186comprises the substrate 172, such as a substrate composed of a polymericmaterial. The adhesive sheet 176 having an adhesive material on at leastone of the top and bottom surfaces is positioned between the substrate172 and an inductor coil 12 formed from the electrically conductivematerial 178. The first adhesive sheet 176 configured to adhere theinductor coil 12 to the surface of the substrate 172. A second adhesivesheet 176 is positioned between a second inductor coil 12 and thesubstrate 172, on the opposite side of the substrate 172.

It will be appreciated that any of the embodiments described herein canbe used with multilayer, multilayer multiturn, multimode and similarlyconfigured structures. The following U.S. Patents Nos. and U.S. PatentApplication Ser. Nos. are additionally incorporated herein fully byreference: U.S. Pat. Nos. 8,567,048; 8,860,545; 9,306,358; 9,439,287;9,444,213; and Ser. No. 15/227,192; 15/240,637.

Thus, it is contemplated that the embodiments of inductor coils andantennas that enable wireless electrical energy transfer embodiments ofthe present disclosure may be configured having a variety ofconfigurations. Furthermore, such configurations of the variety ofinductor coils and antennas allow for significantly improved wirelesstransmission of electrical energy and/or data. It is furthercontemplated that the various magnetic shielding materials 66 can bestrategically positioned adjacent to the transmitting or receivingantennas 22, 26 to enhance quality factor and mutual inductance betweenadjacently positioned transmitting and receiving antennas 22, 26. It isappreciated that various modifications to the subject technologyconcepts described herein may be apparent to those of ordinary skill inthe art without departing from the spirit and scope of the presentdisclosure as defined by the appended claims.

As used herein, the phrase “at least one of” preceding a series ofitems, with the term “and” or “or” to separate any of the items,modifies the list as a whole, rather than each member of the list (i.e.,each item). The phrase “at least one of” does not require selection ofat least one of each item listed; rather, the phrase allows a meaningthat includes at least one of any one of the items, and/or at least oneof any combination of the items, and/or at least one of each of theitems. By way of example, the phrases “at least one of A, B, and C” or“at least one of A, B, or C” each refer to only A, only B, or only C;any combination of A, B, and C; and/or at least one of each of A, B, andC.

The predicate words “configured to”, “operable to”, and “programmed to”do not imply any particular tangible or intangible modification of asubject, but, rather, are intended to be used interchangeably. In one ormore embodiments, a processor configured to monitor and control anoperation or a component may also mean the processor being programmed tomonitor and control the operation or the processor being operable tomonitor and control the operation. Likewise, a processor configured toexecute code can be construed as a processor programmed to execute codeor operable to execute code.

A phrase such as “an aspect” does not imply that such aspect isessential to the subject technology or that such aspect applies to allconfigurations of the subject technology. A disclosure relating to anaspect may apply to all configurations, or one or more configurations.An aspect may provide one or more examples of the disclosure. A phrasesuch as an “aspect” may refer to one or more aspects and vice versa. Aphrase such as an “embodiment” does not imply that such embodiment isessential to the subject technology or that such embodiment applies toall configurations of the subject technology. A disclosure relating toan embodiment may apply to all embodiments, or one or more embodiments.An embodiment may provide one or more examples of the disclosure. Aphrase such an “embodiment” may refer to one or more embodiments andvice versa. A phrase such as a “configuration” does not imply that suchconfiguration is essential to the subject technology or that suchconfiguration applies to all configurations of the subject technology. Adisclosure relating to a configuration may apply to all configurations,or one or more configurations. A configuration may provide one or moreexamples of the disclosure. A phrase such as a “configuration” may referto one or more configurations and vice versa.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” or as an “example” is not necessarily to be construed aspreferred or advantageous over other embodiments. Furthermore, to theextent that the term “include,” “have,” or the like is used in thedescription or the claims, such term is intended to be inclusive in amanner similar to the term “comprise” as “comprise” is interpreted whenemployed as a transitional word in a claim. Furthermore, to the extentthat the term “include,” “have,” or the like is used in the descriptionor the claims, such term is intended to be inclusive in a manner similarto the term “comprise” as “comprise” is interpreted when employed as atransitional word in a claim.

All structural and functional equivalents to the elements of the variousaspects described throughout this disclosure that are known or latercome to be known to those of ordinary skill in the art are expresslyincorporated herein by reference and are intended to be encompassed bythe claims. Moreover, nothing disclosed herein is intended to bededicated to the public regardless of whether such disclosure isexplicitly recited in the claims. No claim element is to be construedunder the provisions of 35 U.S.C. § 112, sixth paragraph, unless theelement is expressly recited using the phrase “means for” or, in thecase of a method claim, the element is recited using the phrase “stepfor.”

Reference to an element in the singular is not intended to mean “one andonly one” unless specifically so stated, but rather “one or more.”Unless specifically stated otherwise, the term “some” refers to one ormore. Pronouns in the masculine (e.g., his) include the feminine andneuter gender (e.g., her and its) and vice versa. Headings andsubheadings, if any, are used for convenience only and do not limit thesubject disclosure.

While this specification contains many specifics, these should not beconstrued as limitations on the scope of what may be claimed, but ratheras descriptions of particular implementations of the subject matter.Certain features that are described in this specification in the contextof separate embodiments can also be implemented in combination in asingle embodiment. Conversely, various features that are described inthe context of a single embodiment can also be implemented in multipleembodiments separately or in any suitable subcombination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to a subcombination or variation of a sub combination.

What is claimed:
 1. An antenna array configured to transmit or receivewireless electrical energy, the antenna array comprising: a firstantenna comprising a first electrically conductive filar with spacedapart first and second filar ends forming a first inductor coil, whereinthe first electrically conductive filar crosses over itself at a firstcrossover intersection thereby forming the first inductor coil as afirst figure-eight configuration, the first figure-eight configurationcomprising a first inductor coil loop and a second inductor coil loopwound in opposite directions, wherein the first crossover intersectionlies between the first inductor coil loop and the second inductor coilloop, and wherein a first imaginary line bisects both the first inductorcoil loop and the second inductor coil loop; a second antenna comprisinga second electrically conductive filar with spaced apart first andsecond filar ends forming a second inductor coil, wherein the secondelectrically conductive filar crosses over itself at a second crossoverintersection thereby forming the second inductor coil as a secondfigure-eight configuration, the second figure-eight configurationcomprising a third inductor coil loop and a fourth inductor coil loopwound in opposite directions, wherein the second crossover intersectionlies between the third inductor coil loop and the fourth inductor coilloop, and wherein a second imaginary line bisects both the thirdinductor coil loop and the fourth inductor coil loop; and a thirdantenna comprising a third electrically conductive filar with spacedapart first and second filar ends forming a third inductor coil, whereinthe third electrically conductive filar crosses over itself at a thirdcrossover intersection thereby forming the third inductor coil as athird figure-eight configuration, the third figure-eight configurationcomprising a fifth inductor coil loop and a sixth inductor coil loopwound in opposite directions, wherein the third crossover intersectionlies between the fifth inductor coil loop and the sixth inductor coilloop, and wherein a third imaginary line bisects both the fifth inductorcoil loop and the sixth inductor coil loop; wherein the first, second,and third antennas are arranged so that (i) a first inductor coil arrayangle extends between the first imaginary line and the third imaginaryline and a second inductor coil array angle extends between the secondimaginary line and the third imaginary line, wherein a sum of the firstand second inductor coil array angles is equal to or greater than 1° andequal to or less than 90°, (ii) the first and second inductor coils areco-planar, (iii) the third inductor coil is positioned on a plane aboveor below the first and second inductor coils, and (iv) the thirdinductor coil at least partially overlaps both the first and secondinductor coils; and wherein the antenna array is operatively coupledwith a controller configured to selectively connect one or more of thefirst, second, or third antennas to an electrical power source towirelessly transmit or receive the electrical energy to or from anexternal device.
 2. The antenna array of claim 1, wherein the firstinductor coil has a first number of turns, wherein the second inductorcoil has a second number of turns, and wherein the first number of turnsis greater than the second number of turns.
 3. The antenna array ofclaim 1, wherein at least one of the first, second, or third inductorcoils is tuned to an operating frequency.
 4. The antenna array of claim3, wherein the first, second and third inductor coils are each tuned toa different operating frequency.
 5. The antenna array of claim 3,wherein the operating frequency is in the range of 6.78 MHz to 276.12MHz.
 6. The antenna array of claim 3, wherein the operating frequency isin the range of 50 kHz to 500 kHz.
 7. The antenna array of claim 1,wherein the sum of the first and second inductor coil array angles is90°.
 8. The antenna array of claim 1, wherein the first and secondinductor coil array angles are equal to each other.
 9. The antenna arrayof claim 1, wherein the antenna array is embedded within one of aplatform or a substrate.
 10. The antenna array of claim 9, wherein apotting compound is used to embed the antenna array within the platformor the substrate.
 11. The antenna array of claim 10, wherein the pottingcompound comprises an adhesive, a thermosetting adhesive, a polymericmaterial, a thermoplastic polymer, a dielectric material, a metal, or aceramic material.
 12. The antenna array of claim 10, wherein the pottingcompound has a thermal conductivity equal to or greater than 1.0W/(M·K).
 13. The antenna array of claim 1, wherein the first inductorcoil array angle is 45°, and wherein the second inductor coil arrayangle is 45°.
 14. The antenna array of claim 1, wherein the firstinductor coil is configured to generate a first inductance at a firstresonant frequency, wherein the second inductor coil is configured togenerate a second inductance at a second resonant frequency, and whereinthe third inductor coil is configured to generate a third inductance ata third resonant frequency.
 15. The antenna array of claim 14, whereineach of the first, second and third resonant frequencies is in the rangeof 1 kHz to 1 MHz.
 16. The antenna array of claim 14, wherein two ormore of the first, second, or third inductances have differentinductance values.
 17. The antenna array of claim 14, wherein each ofthe first, second and third inductances is in the range of 50 nH to 50μH.